By bundling the shaded 1.9.1 version of JUnit Platform, it addresses issues finding the method org.junit.platform.commons.util.CollectionUtils.isConvertibleToStream which is required by JUnit Jupiter 5.9.1. The JUnit Platform is backwards compatible with older versions of Jupiter, at least back to 5.8.2.
By bundling the shaded 1.9.1 version of JUnit Platform, it addresses issues finding the method org.junit.platform.commons.util.CollectionUtils.isConvertibleToStream which is required by JUnit Jupiter 5.9.1. The JUnit Platform is backwards compatible with older versions of Jupiter, at least back to 5.8.2.